Aircraft security system

ABSTRACT

The security system provides an aircraft security system capable of protecting both single and multiple engine aircraft. Variations of the present system prevent unauthorized starting of protected aircraft and activate an alarm when engine starting it is attempted. Embodiments of the system draw no power from the aircraft when the security system is armed and in no way interferes with the normal starting or operation of the aircraft when the system is disarmed. Embodiments of the present system can activate an alarm when an aircraft&#39;s doors or panels are opened. Embodiments of the present invention can activate an alarm when installed equipment or other devices are tampered with or removed from their housings.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.12/197,538, filed Aug. 25, 2008, which is a continuation of U.S. Pat.No. 7,423,554, Ser. No. 11/138,652, filed May 26, 2005, whichapplication claims the benefit under 35 U.S.C. 119(e) from U.S.Provisional Application Ser. No. 60/576,262, filed Jun. 2, 2004, whichare incorporated herein by reference in their entirety.

FIELD OF INVENTION

This application relates generally to methods and apparatus for anaircraft security and alarm system.

BACKGROUND

The physical security of aircraft is historically poor on most aircraftin operation today. Aside from the ignition switches, the only securityprovided on most aircraft is key-type door locks which are generally ofpoor quality and can be readily opened with a wide variety of keys. Onceinside the aircraft, an intruder has easy access to a multitude ofeasily removable and often expensive avionics and instrumentationdevices. Engine ignition is also easily accomplished by an unauthorizedperson. For example, most single engine aircraft have key-type,turn-to-start ignition switches. The switch units are readily accessibleand clearly marked on the back as to the function of each terminal,making the switch units easily bypassed and/or hot wired to achieveignition. Multi-engine aircraft have no start security in that they haveonly toggle and/or push-button ignition switches.

Accordingly, there is a need for an aircraft security system that issimple, light-weight, easy to install in new and existing aircraft, andis difficult to detect by an unauthorized person—yet prevents operationof the aircraft when armed. In addition, there is a need for a securitysystem that does not draw power from the aircraft when armed, and isfunctional only when the aircraft is on the ground and parked.

SUMMARY

The various embodiments described herein relate to methods and apparatusof an aircraft security system. The teachings provided herein solve theearlier mentioned problems and additional problems not stated herein.

_write

This summary is an overview of some of the teachings of the presentapplication and is not intended to be an exclusive or exhaustivetreatment of the present subject matter. Further details about thepresent subject matter are found in the detailed description below andin the appended claims. Other aspects of the system will be apparent topersons skilled in the art upon reading and understanding the followingdetailed description and viewing the drawings that form a part thereof,each of which are not to be taken in a limiting sense. The scope of thepresent system is defined by the appended claims and their legalequivalents.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A illustrates a block diagram of one embodiment of the presentAircraft Security System configured for both single and multi engineaircraft.

FIG. 1B illustrates a block diagram of one embodiment of the presentAircraft Security System configured for both single and multi engineaircraft.

FIG. 2 illustrates a schematic view of one embodiment of the presentAircraft Security System configured for single engine aircraft.

FIG. 3 illustrates a schematic view of one embodiment of the presentAircraft Security System configured for multi engine aircraft.

FIG. 4 illustrates a schematic view of one embodiment of the presentAircraft Security System configured for single engine aircraft.

FIG. 5 illustrates a schematic view of one embodiment of the presentAircraft Security System configured for multi engine aircraft.

DETAILED DESCRIPTION

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the various embodiments. It will be apparent, however,to one skilled in the art that the various embodiments may be practicedwithout some of these specific details. The following description anddrawings provide examples for illustration, but are not intended in alimiting sense and are not intended to provide an exhaustive treatmentof all possible implementations.

It should be noted that references to “an embodiment” or “oneembodiment” in this disclosure are not necessarily to the sameembodiment, and such references may contemplate more than oneembodiment. Further, the terms “bus” and “buss” are used interchangeablythroughout the specification and in the drawings.

Further, references made to actuation of a switch may include opening orclosing of a switch. It is understood that embodiments demonstrating acircuit having a switch in a first state may also be reconfigured to acircuit having a switch in a second state without departing from thescope of the present subject matter. Thus, an embodiment having anormally closed switch may be realized in an embodiment having anormally open switch without departing from the present subject matter.Those of skill in the art upon reading and understanding the presentapplication will appreciate that differences in configuration andcomponents may be employed without departing from the scope of thepresent teachings.

FIG. 1A illustrates a block diagram of one embodiment of an aircraftsecurity system 100, including block 71 including an aircraft battery,block 72 including an aircraft master switch and an electrical buss,block 73 including an anti-theft system, block 74 including one or moreaircraft starter switches for single and multiple engines, and block 75including one or more aircraft starter relays and starter motors forsingle and multiple engines. FIG. 1A illustrates blocks 71, 72, 73, 74,and 75 as being coupled by connections 80, 81, 82, and 83 all beingshown as a single line. However, it will be realized by those ofordinary skill in the art that connections 80, 81, 82, and 83 mayinclude one or more conductors and one or more other forms of electricalor mechanical couplings between blocks 71, 72, 73, 74, and 75 withoutdeparting from the scope of the present subject matter.

In one embodiment, the aircraft battery of block 71 couples throughconnection 80 to the aircraft master switch and electrical buss of block72. In one embodiment, the aircraft master switch of block 72, whenclosed, allows power from the aircraft battery to reach the electricalbuss of block 72, and when the aircraft master switch is open, powerfrom the aircraft battery is disconnected from the electrical buss. Whenthe master switch is closed, power from the electrical buss of block 72is coupled through connection 81 to the anti-theft system of block 73.In one embodiment, the anti-theft system operates in both an activatedor armed mode, and a deactivated or unarmed mode. The apparatus andmethods for determining the modes and operations of the anti-theftsystem are described in further detail below.

If power from block 72 reaches block 73 and the anti-theft system isactivated, the anti-theft system will disconnect the power supplied fromblock 72, and thus not allow power for the aircraft battery to powerblock 74 or block 75. By not allowing power to reach blocks 74 and 75,the anti-theft system of block 73 prevents the starting of the engine orengines present on the aircraft, even if the aircraft starter switch orswitches of block 74, as described below, are actuated (closed).

If power from block 72 reaches block 73 and the anti-theft system isdeactivated, the anti-theft system will allow the power to be coupledthrough connection 82 to block 74. In various embodiments, block 74includes one aircraft starter switch, associated with the singe engineof a single engine aircraft. If power is supplied to block 74 and theaircraft starter switch is actuated (closed), power will be coupledthrough connection 83 to block 75. In various embodiments, block 75includes an aircraft starter relay that will be energized by the powersupplied through connection 83. When energized, the aircraft starterrelay will allow power to reach the starter motor associated with theaircraft engine, and thus allow starting of the aircraft's engine.

In various embodiments, block 74 includes multiple aircraft starterswitches, wherein each of the switches is associated with one of theengines of a multiple engine aircraft. If power is supplied to block 74and one of the aircraft starter switches of block 74 is actuated(closed), power will be coupled through connection 83 to block 75. Itwill be realized by those of ordinary skill in the art that for multipleengine applications, connection 83 may include separate connectionsassociated with each of the engines of the multiple engine aircraft. Invarious embodiments, block 75 includes multiple aircraft starter relays,each one being associated with a starter motor. When power is suppliedto block 75 through connection 83, the particular starter relayassociated with the starter switch being actuated will be energized.When energized, the particular starter relay energized will allow powerto reach the aircraft starter motor associated with that starter relay,allowing the aircraft engine associated with that starter motor to bestarted.

As described above with regards to a single engine aircraft, for amultiple engine aircraft, if power from block 72 reaches block 73 andthe anti-theft system is activated, the anti-theft system willdisconnect the power supplied from block 72, and thus not allow powerfrom the aircraft battery of block 71 to power block 74 or block 75. Bynot allowing power to reach blocks 74 and 75, the anti-theft systemprevents starting of the engines present on the aircraft, even if theaircraft starter switch of the one or more starter switches of block 74are actuated (closed). Thus, when activated, the anti-theft systemprevents starting for any of the engines on the multiple engineaircraft.

FIG. 1B illustrates a block diagram of one embodiment of an aircraftsecurity system 110. The embodiment of aircraft security system 110 issimilar to the embodiment of system 100, except that block 74 (aircraftstarter switch -single and multiple engine) is coupled to block 72through connection 81, and block 74 is further coupled to the anti-theftsystem of block 73 through connection 82. The anti-theft system of block73 is coupled to block 75 through connection 83. System 110 functions ina similar manner to system 100. However, one embodiment may be preferredover the other with regards to installment of the system on an aircraftdue to, among other factors, physical access to the various portions ofthe circuits in the aircraft.

FIG. 2 illustrates one embodiment of an aircraft security system 200including a starter breaker 4 electrically connected to main power bus 3and a starter switch 5, where the main power bus 3 is powered by amaster switch 2 from a main battery 1. In various embodiments, mainpower bus 3 may be an instrument bus. System 200 further includes asecurity relay 11 having activation means for a first set of contacts 20and a second set of contacts 21, where the first set of contacts 20 arenormally closed, and are electrically connected to a starter switch 5, astarter relay 6, and where the second set of contacts 21 are normallyopen and are electrically connected to a remote battery 14, a remoteswitch 12, an alarm 13, and a diode 10A. A security switch 9 iselectrically connected to the security relay 11. In one embodiment,security switch 9 is a key lock switch. Other embodiments havingdifferent types of switches are possible without departing from thescope of the present subject matter.

System 200 includes one or more modes of operation. In normal, unarmedoperation, security switch 9 is open, and the control coil of securityrelay 11 is de-energized. In this mode, normally closed contacts 20 ofsecurity relay 11 will be in a closed state. Activation of the masterswitch 2 and the starter switch 5 in this mode causes current to flowthrough the normally closed contacts 20 of the security relay 11,allowing current flow from main power bus 3 and starter breaker 4, tothe starter relay 6, which, when energized, closes contacts 22 ofstarter relay 6. With contacts 22 closed, power is delivered to startermotor 7 from starter bus 23 through electrical connection 55, contacts22, and electrical connection 56.

In another mode of operation of system 200, security switch 9 is closed.The control coil of security relay 11 is electrically coupled to mainpower bus 3 through electrical connection 60, security switch 9,electrical connection 57. In one embodiment, diode 10B coupleselectrical connection 60 with electrical connection 59, electricalconnection 59 being coupled to security switch 9. Activation of masterswitch 2 with a closed (armed) security switch 9 allows current frommain battery 1 to flow through master switch 2 to the main power bus 3,and thus energizes the control coil of security relay 11, causingnormally closed contacts 20 to open. With normally closed contacts 20open, the current flow from the main power bus 3 to starter relay 6 isdisconnected. Starter relay 6 remains de-energized, and contacts 22remain open. With contacts 22 open, no power is delivered to startermotor 7 from the starter bus 23. With normally closed contacts 20 open,activation of starter switch 5 will not allow power from main battery 1to energize starter relay 6, and thus will prevent starting of theaircraft.

FIG. 2 illustrates an embodiment of the security system 200 in which atleast one application is configured for single engine aircraft. Duringnormal operation, the master switch 2 is closed, allowing battery powerfrom the main battery 1 to flow to the main power bus 3 throughelectrical connections 50 and 51. During a normal ignition sequence,current flows from the main power bus 3 through electrical connection 67to starter breaker 4, then through electrical connection 52 to starterswitch 5. When starter switch 5 is actuated (closed), current flowsthrough starter switch 5, and through electrical connection 58 to thenormally closed contacts 20 of the security relay 11. From normallyclosed contacts 20, current flows through electrical connection 54,energizing the control coil of starter relay 6, and closing contacts 22,providing power to the engine starter motor 7 from starter bus 23through electrical connection 55, contacts 22, and electrical connection56.

In various embodiments, the security switch 9 includes, but is notlimited to, a toggle switch, a key pad, or a biometric security devicewhich is activated for proper operation of the aircraft. In variousembodiments, activation may include entering a Personal IdentificationNumber (PIN) on a key pad before proper operation of the aircraft willbe enabled. In various embodiments, the function and location of thesecurity switch 9 is known only to authorized operators of the aircraft.In one or more embodiments, when the owner/operator desires security,the normally open security switch 9 is closed. Once security switch 9 isclosed, activating the master switch 2 causes current to flow from themain power bus 3 along electrical connection 57 to the now closed(armed) contacts of the security switch 9. Power is now available,through electrical connection 60, to the control coil of security relay11, activating security relay 11. In various embodiments, the path ofcurrent flow includes electrical connection 59 and diode 10B.

Activation of security relay 11 causes various events to occur. In anembodiment, the energized security relay 11 opens the normally closedcontacts 20, thus opening the start circuit and preventing starter motor7 from energizing, even when starter switch 5 is actuated, or if starterswitch 5 is tampered with. For example even if the “S” and “B” terminalsof starter switch 5, as illustrated in FIG. 2, are jumpered or otherwiseshorted, the normally open contacts 20 will prevent power from beingdelivered to starter relay 6, and thus prevent starting of theaircraft's engine.

In various embodiments, the energization of security relay 11 will closenormally open contacts 21. With normally open contacts 21 closed,current can flow from remote battery 14 through electrical connection 61and through remote switch 12 and through electrical connection 62, andthrough the now closed normally open contacts 21 of the security relay11. Current then continues to flow through electrical connection 63 anddiode 10A to electrical connection 60, providing a second source ofcurrent flow through the control coil of security relay 11, keepingsecurity relay 11 energized (latched). In various embodiments, thecurrent flow to electrical connection 63 will allow alarm 13 to becomeactivated. Once latched, security relay 11 and alarm 13 will remainactivated even if starter breaker 4 is opened or if the aircraft'sprimary power is removed from the main power bus 3 by opening theaircraft's master switch 2. Alarm 13 is deactivated by opening thecontacts of remote switch 12. In various embodiments, the function andlocation of the remote switch 12 is known only to the owner/operator ofthe aircraft or other authorized persons.

FIG. 3 illustrates an embodiment where the security system 300 is usefulin applications, including, but not limited to, use in multiple engineaircrafts. Reference numbers are repeated for elements of FIG. 3 whichare the same or similar to those of FIG. 2. Elements in FIG. 3 depictingadditional iterations of the same or similar elements as depicted inFIG. 2 are shown using the same reference numbers with the addition of aletter, for example, “A” or “B.” According to various embodiments ofsystem 300, during normal operation, master switch 2 is activatedallowing battery power to flow from main battery 1 to main power bus 3.During a normal ignition sequence, current flows from main power bus 3through electrical connection 67 and starter breaker 4, then throughelectrical connection 52 to the normally closed contacts 20 of securityrelay 11. In various embodiments, the current continues to flow throughelectrical connections 53A and 53B to the normally open contacts of theengine starter switches 5A and 5B respectively. In various embodiments,current also flows to additional engine starting circuits, for example,electrical connections 53C and 53D to the normally open contacts ofstarter switches 5C and 5D respectively. For purposes of illustration,only the complete starting circuits associated with starter switches 5Aand 5B are shown and further discussed in detail. However, it will berecognized by those skilled in the art that similar iterations of thesecircuits could be duplicated without departing from the scope of thepresent subject matter.

In one embodiment, starter switches 5A and 5B are operated by separatemeans. In one embodiment, starter switches 5A and 5B may be operated atseparate times. When starter switch 5A is activated, current flowsthrough its closed contacts and electrical connection 54A to theassociated starter relay 6A, energizing the control coil of starterrelay 6A, and closing contacts 22A. With contacts 22A closed, currentfrom starter bus 23A flows through electrical connection 55A, contacts22A, and electrical connection 56A to power starter motor 7A. Thus, thestarting of the aircraft's engine associated with starter motor 7A isenabled.

When the starter switch 5B is activated, current flows through itsclosed contacts and electrical connection 54B to the associated enginestarter relay 6B, energizing the control coil of starter relay 6B, andclosing contacts 22B. With contacts 22B closed, current from starter bus23B flows through electrical connection 55B, contacts 22B, andelectrical connection 56B to power starter motor 7B. Thus, the startingof the aircraft's engine associated with starter motor 7B is enabled.

As discussed above, various embodiments of security system 300 includeadditional electrical connections 53C and 53D that are coupled tostarter switches 5C and 5D respectively. These additional circuits andstarter switches are coupled to additional starter relays (not shown)and starter motors (not shown). It will be realized by those of skill inthe art that additional circuits and various combinations of starterswitches are possible without departing from the scope of the presentsubject matter.

In various embodiments, the function and location of the security switch9 is known only to authorized operators of the aircraft. When theowner/operator desires security, security switch 9 is activated(closed). In an embodiment, when security switch 9 is activated and anunauthorized start is attempted, current flows from main power bus 3,through electrical connection 57 and the now closed security switch 9,through electrical connection 60, and to the control coil of securityrelay 11, thus activating security relay 11. In one embodiment,electrical connection 60 is coupled to security switch 9 throughelectrical connection 59 and diode 10B.

When security relay 11 is activated, various events occur. In anembodiment, the normally closed contacts 20 of the security relay 11open, removing power from the starter switches 5A and 5B, and preventingeither of the engines from being started, even if starter switches 5A or5B are actuated. In an embodiment, when security relay 11 is activated,the normally open contacts 21 of security relay 11 close, allowing powerto flow from the remote battery 14 through the remote switch 12 andelectrical connections 61, and 62, through the now closed contacts ofnormally open contacts 21, and through electrical connection 63 to theaudio alarm 13. Current also flows from electrical connection 63 throughdiode 10A to keep the security relay 11 activated (latched) even if thestarter breaker 4 is reopened or when the aircraft's primary power isremoved from the main power bus 3 by re-opening the aircraft's masterswitch 2. In one embodiment, once security switch 9 is opened (unarmed),the audible alarm 13 is turned off by opening remote switch 12. Thisremoves power from the alarm 13 as well as from the control coil of thesecurity relay 11, unlatching security relay 11. Unlatching securityrelay 11 causes normally open contacts 21 to open, and normally closedcontacts 20 to close.

FIG. 4 illustrates an embodiment of the security system 400 enhanced toprovide security against unauthorized entry and unauthorized removal ofinstalled devices. The embodiment is shown for single engine aircraft,but is equally applicable to multi-engine aircraft as shown in FIG. 5.Reference numbers are repeated for elements of FIG. 4 that are the sameor similar to those of FIG. 2. Elements in FIG. 5 depicting additionaliterations of the same or similar elements as depicted in FIG. 4 areshown using the same reference numbers with the addition of a letter,for example, “A” or “B.”

Various embodiments of security system 400 are enhanced to includesecurity switch 9 coupled to main power bus 3 through electricalconnection 57 and a circuit protection device, for example, an in-linefuse 26, is included between electrical connections 57 and 58.Electrical connection 58 couples circuit 24 of security switch 9 throughdiode 10B to electrical connection 60, which then is coupled to the coil(the control portion) of security relay 11. When security switch 9 isclosed (armed) and master switch 2 is activated, power from main battery1 flows from main battery 1 through master switch 2 and main power bus3, and further through circuit 24 of security switch 9 to energize thecoil of security relay 11.

Once activated, security relay 11 opens normally closed contacts 20 andcloses normally open contacts 21, latching security relay 11 throughremote battery 14 and remote switch 12 while preventing the powering ofstarter relay 6, as described above. Further, in various embodiments,alarm 13 is activated when security relay 11 is energized.

As illustrated in FIG. 4, in various embodiments of system 400, aircraftdoors and removable equipment are protected with switches 15 and 16. InFIG. 4, switches 15 and 16 are shown as magnetic switches. However,switches 15 and 16 are not limited to being magnetic switches. In oneembodiment, switches 15 and 16 are motion activated. In an embodiment,switches 15 and 16 are proximity switches. In various embodiments, othertype switches are possible, including, but not limited to, optical, Halleffect, pressure, or other types of switches, such as proximity ormotion activated switches. In various embodiments, additional switchesare included. In various embodiments, switches 15 and 16 will not be thesame type of switch. It will be recognized that various type switches,and various combinations of types of switches, may be used in a varietyof applications and in various combinations. In various embodiments,switches 15 and 16 are in communication with system 400 using a wirelessform of coupling.

In various embodiments, switches 15 and 16 are arranged so that when adoor or a hatch of the aircraft is opened, or in the case of installedequipment, the equipment is tampered with or removed from its housing,the associated switch 15 or 16 is actuated. This allows current to flowfrom remote battery 14 through electrical connection 61 and remoteswitch 12, on through electrical connection 64 and the now actuatedcontacts of switches 15 or 16, then on through electrical connection 65to the circuit 25 of the security switch 9. If the security system isset on (armed), the circuit 25 of security switch 9 will be closed,allowing current to flow through electrical connection 66 and diode 10Cto activate and latch security relay 11, as discussed above. In variousembodiments, alarm 13 is also activated when security relay 11 isactivated or latched. In various embodiments, alarm 13 includes anaudible alarm. In various embodiments, the alarm is a silent alarm. Invarious embodiments, alarm 13 includes notification of the activation ofthe alarm to one or more various parties, including but not limited to,the aircraft owner, the aircraft operator, airport security officials,and law enforcement officials.

In one embodiment, activation of security relay 11 will cause normallyclosed contacts 20 to open, and thus prevent starting of the engineassociated with starter motor 7, even if starter switch 5 is tamperedwith as discussed above. In an embodiment, alarm 13 is turned off byopening remote switch 12 as discussed above.

FIG. 5 illustrates an embodiment where the security system 500 is usefulin applications, including, but not limited to, use in multiple engineaircrafts. Reference numbers are repeated for elements of FIG. 5 whichare the same or similar to those of FIG. 4. Elements in FIG. 5 depictingadditional iterations of the same or similar elements as depicted inFIG. 4 are shown using the same reference numbers with the addition of aletter, for example, “A” or “B.”

As illustrated in FIG. 5, in various embodiments of system 500, aircraftdoors and removable equipment are protected with switches 15 and 16. Invarious embodiments, switches 15 and 16 are arranged so that when thedoor or hatch of the aircraft is opened, or in the case of installedequipment, the equipment is tampered with or removed from its housing,the associated switch 15 or 16 is actuated. In various embodiments,switches 15 and 16 are in communication with the system 500 through awireless coupling. In various embodiments, if either of switches 15 or16 actuate when security switch 9 is activated (armed), security relay11 will be energized, and normally closed contacts 20 will open. Withnormally closed contacts 20 open, power is disconnected from starterswitches 5A and 5B, and thus activation of either of starter switches 5Aor 5B, even if tampered with or bypassed, will not enable the startingof either of the aircraft's engines associated with starter relays 6Aand 6B. In various embodiments, if provided, additional engine startingcircuits, for example, circuits associated with starter switches 5C and5D (associated starter relays and starter motors not shown), would alsobe disconnected from power, and thus would also disable the starting ofthe aircraft's engine associated with that circuit.

In various embodiments of system 500, activation of security relay 11will latch relay 11. In various embodiments, alarm 13 is also activatedwhen security relay 11 is activated or latched. In an embodiment, alarm13 is turned off by opening remote switch 12 as discussed above.

This description has set forth numerous characteristics and advantagesof various embodiments and details of structure and function of anaircraft security system, but is intended to be illustrative and notintended in an exclusive or exhaustive sense. Changes in detail,material and management of parts, order of process and design may occurwithout departing from the scope of the appended claims and their legalequivalents.

1. A system for securing an aircraft having a starter, a starter switch,and a master switch to connect, in an on position, a first power sourceto a main power bus, the system comprising: a security system connectedto control power to the starter, the security system including: asecurity switch adapted to arm the security system in an armed state andto disarm the security system in a disarmed state; a second power sourceto provide backup power to the security system; a controllable switchadapted to complete a starter circuit for powering the starter in afirst mode and to break the starter circuit in a second mode, thecontrollable switch adapted to be controlled by sensing states of atleast the security switch and the main power bus, and wherein in thearmed state the security system is configured to prevent activation ofthe starter upon detection of attempted use of the aircraft beforedisarming the security system.
 2. The system of claim 1, whereinattempted use of the aircraft before disarming the security systemincludes the master switch being in the on position.
 3. The system ofclaim 1, wherein the second power source is connected to thecontrollable switch and is adapted to maintain the controllable switchin the second mode once the controllable switch has entered the secondmode.
 4. The system of claim 1, further including a remote switch toreset the security system when the security system is activated.
 5. Thesystem of claim 1, further including the controllable switch beingadapted to be controlled by sensing states of one or more switchesconnected to the second power source.
 6. The system of claim 5, whereinone or more switches connected to the second power source includes aswitch associated with a door of the aircraft.
 7. The system of claim 5,wherein one or more switches connected to the second power sourceincludes a switch associated with an installed device of the aircraft.8. The system of claim 1, further including an alarm coupled to thesecurity system.
 9. The system of claim 1, wherein the second powersource is coupled to the alarm and is adapted to power the alarm untildisconnected using a remote switch to reset the security system once thesecurity system is activated.
 10. The system of claim 1, wherein in thearmed state the security system is configured to prevent activation of asecond starter upon detection of attempted use of the aircraft beforedisarming the security system.
 11. An aircraft electrical systemcomprising: a master switch connected to a battery; a starter relayhaving a starter switch interconnecting the main switch to the starterrelay; a security switch connected to the main switch; and a securityrelay having a coil connected to the security switch; wherein thesecurity relay interconnects the main switch and the starter relay in acoil unpowered state of operation, and further disconnects the mainswitch and the starter relay and interconnects a remote battery and thecoil in a coil powered state of operation.
 12. The system of claim 11,wherein a normally closed set of contacts of the security relayinterconnects the main switch and the starter relay in the coilunpowered state of operation.
 13. The system of claim 11, wherein anormally open set of contacts of the security relay interconnects theremote battery and the coil in the coil powered state of operation. 14.The system of claim 13, wherein a remote switch interconnects the remotebattery and the normally open set of contacts of the security relay. 15.The system of claim 11, further including an alarm, wherein the alarminterconnects to the remote battery in the coil powered state ofoperation.
 16. The system of claim 11, further including a switch,wherein the switch interconnects the remote battery through the securityswitch to the coil.
 17. The system of claim 16, wherein the switch isadapted to interconnect the remote battery through the security switchto the coil when a door associated with the switch is opened.
 18. Thesystem of claim 16, wherein the switch is adapted to interconnect theremote battery through the security switch to the coil when an installeddevice associated with the switch is removed.
 19. The system of claim11, wherein the security relay interconnects the main switch and aplurality of starter relays in the coil unpowered state of operation.20. An apparatus for securing an aircraft, comprising: a first powersupply; a starter and starter relay for use in starting an engine of theaircraft; a main power bus and master switch providing power to thestarter relay and starter; and switch means for controllablydisconnecting the first power supply from the starter relay and starterupon detection of an attempted intrusion while in an armed state. 21.The apparatus of claim 20, further comprising alarm means.
 22. Theapparatus of claim 20, further comprising a second starter and a secondstarter relay for use in starting a second engine of the aircraft.